This Mentored Research Scientist Development Award (K01) application requests support for five years to investigate how risk and protective factors combine to put pre-teens at some overall drug use liability level. Many risk and protective factors pertaining to drug use, and dependence have been identified, however, few studies have investigated the association between risk factors among children prior to their first ingestion of drugs and later drug use, abuse, and dependence. Even fewer studies have examined how the various risk and protective factors combine to put individuals at some overall risk for (liability to) substance use. Under the mentorship of experts in psychopathological assessment, this study would a) develop a computer-administered instrument titled the Assessment of Liability and EXposure to Substance Use (ALEXSU) and b) prospectively test competing models of drug misuse liability. The ALEXSU would a) not require minimum reading or writing levels, b) be computerized because computer- based assessments of drug abuse generate increased reporting of substance use (Reich, et al., 1995; Turner, et al., 1998), and c) be enhanced with developmentally appropriate and culturally neutral graphics. The research plan proposes to a) develop the ALEXSU from existing measures designed for older individuals, b) investigate the ALEXSU's one-week test-retest reliability among 9 to 12 year old children, c) investigate how well ALEXSU scores predict stages of use and drug-related psychiatric symptoms for a variety of legal and illicit substances two years later and d) test three competing models of drug use liability against each other against a model that combines them, and against a simple summation score of the number of risk factors that participants report. Samples represent high- and low-risk populations. Small-scale validity studies of the ALEXSU will be conducted. Competing liability models will be compared in terms of how accurately they predict three drug use variables (having tried a drug, stage of drug use, and having an abuse or dependence symptom) at the two-year follow-up. The execution of the proposed research plan, formal coursework, and mentoring from the Sponsor and Co-Preceptors will facilitate the Applicant's a) transition in scientific focus to substance use, abuse, and dependence; b) acquisition of advanced analytical skills regarding substance use assessment and d) a platform from which to pursue a career of independently funded substance use research.